Reconstruction of proximal humeral bone defects in the setting of shoulder revision arthroplasty by implantation of a modular humeral component.Severe segmental humeral bone defects in revision total shoulder arthroplasty, after tumor resection, trauma, pathological fractures, post-infectious or after failed osteosynthesis.Acute or chronic local infections, large diaphyseal bone defects preventing adequate anchorage of the prosthesis, very short life expectancy (<3 months).Removal of the implant using an extended deltopectoral approach. Periarticular arthrolysis with preservation of neurovascular structures. Resection of the meta-diaphyseal bone and reconstruction of the humeral length with the help of different extension sleeves and a modular humeral component. Soft tissue management is crucial, especially with reverse shoulder arthroplasty.Three weeks postoperatively immobilization in a shoulder sling, active assisted movement therapy by gradual pain-adapted increase of movement, muscle coordination, and strength.The results of 11 consecutive patients treated with a modular humeral component due to a failed shoulder arthroplasty between 2008 and 2016 were evaluated retrospectively. Mean length of reconstruction was 100 mm. Due to recurrent dislocations one patient required revision and conversion to a reverse component. No cases of aseptic loosening or periprosthetic infection were observed.